Book/Dissertation / PhD Thesis

FZJ-2022-01955

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Spectral induced polarization of calcite precipitation in porous media

Izumoto, S. (Corresponding author)FZJ*

2022
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-614-4

Please use a persistent id in citations: http://hdl.handle.net/2128/31075  urn:nbn:de:0001-2022051828

Abstract: Precipitation and dissolution dynamics of calcite in response to variations in groundwater pH andalkalinity are important in a range of subsurface engineering applications. In the context of geotechnicalengineering and subsurface remediation applications, induced calcite precipitation is widely used. Theeffectiveness of induced calcite precipitation is typically investigated by measuring hydraulic pressure,analysing biochemical properties of sampled solution, and cone penetration tests. However, thesemethods are spatially and temporally limited, expensive and laborious. Geophysical methods havepotential to overcome these limitations. In particular, Spectral Induced Polarization (SIP) measurementshave been shown to be sensitive to calcite precipitation. However, previous experimental studiesshowed inconsistent SIP responses and have not explored what controls the SIP response of calcite. Inthis context, the overall aim of this thesis was to better understand how spatially variable and temporallydynamic calcite precipitation processes affect the SIP response.In a first step, the effect of solute concentration on the SIP response of calcite precipitation wasinvestigated by a four-phase experiment with SIP measurements on a column filled with sand. In phaseI, Na2CO3 and CaCl2 solutions were co-injected, which resulted in a calcite precipitation front thatincreased the imaginary part of the electrical conductivity (𝜎"). In phase II, several diluted (but stilloversaturated) solutions were injected into the sample with calcite precipitation from phase I, whichresulted in a decrease of 𝜎". The results suggested that the 𝜎" associated with calcite depends morestrongly on the solute conductivity than in the case of sand and sandstone. In phase III, the solutionsfrom phase I were injected first and then the injection was stopped. Since calcite precipitation continuedafter stopping the flow, this resulted in a decrease of the solute concentration in the mixing zone and anassociated decrease of 𝜎". In phase IV, the injection rate of the Na2CO3 solution was reduced relativeto that of the CaCl2 solution. This shifted the mixing zone away from the calcite precipitation front andagain the 𝜎" decreased. These results clearly suggested that the SIP response of calcite is sensitive tothe solute concentration near the precipitates.

Note: Dissertation, Univ. Stuttgart, 2021

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Contributing Institute(s):

1. Agrosphäre (IBG-3)

Research Program(s):

1. 2173 - Agro-biogeosystems: controls, feedbacks and impact (POF4-217) (POF4-217)

Appears in the scientific report 2022

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